1. Field of the Invention
The present invention is generally related to medical methods, apparatus, and kits. More particularly, the present invention is related to methods, systems, and kits for performing discontinuous flow-through peritoneal dialysis.
Patients afflicted with end stage renal disease where kidney transplantation is unavailable may be treated by hemodialysis or peritoneal dialysis to remove toxic products from the patient's blood. Both techniques operate by the principles of diffusion across semipermeable membranes. In the case of peritoneal dialysis, the membrane that is used is the patient's peritoneal membrane.
Peritoneal Dialysis (PD) periodically infuses sterile aqueous solution into the peritoneal cavity. This solution is called peritoneal dialysis solution, or dialysate. Diffusion and osmosis exchanges take place between the solution and the bloodstream across the natural body membranes. These exchanges remove the waste products that the kidneys normally excrete. The waste products typically consist of solutes like sodium and chloride ions, and the other compounds normally excreted through the kidneys like urea, creatinine, and water. The diffusion of water across the peritoneal membrane during dialysis is called ultrafiltration. Conventional peritoneal dialysis solutions include dextrose in concentrations sufficient to generate the necessary osmotic pressure to remove water from the patient through ultrafiltration.
Continuous Ambulatory Peritoneal Dialysis (CAPD) is a popular form of PD. A patient performs CAPD manually about four times a day. During CAPD, the patient drains spent peritoneal dialysis solution from his/her peritoneal cavity. The patient then infuses fresh peritoneal dialysis solution onto his/her peritoneal cavity. This drain and fill procedure usually takes about one hour.
Automated Peritoneal Dialysis (APD) is another popular form of PD. APD uses a machine, called a cycler, to automatically infuse, dwell, and drain peritoneal dialysis solution to and from the patient's peritoneal cavity. APD is particularly attractive to a PD patient, because it can be performed at night while the patient is asleep. This frees the patient from the day-to-day demands of CAPD during his/her waking and working hours.
The APD sequence typically last for several hours.
It often begins with an initial drain cycle to empty the peritoneal cavity of spent dialysate. The APD sequence then proceeds through a succession of fill, dwell, and drain phases that follow one after the other. Each fill/dwell/drain sequence is called a cycle. During the fill phase, the cycler transfers a predetermined volume of fresh, warmed dialysate into the peritoneal cavity of the patient. The dialysate remains (or "dwells") within the peritoneal cavity for a time. This is called the dwell phase. During the drain phase, the cycler removes the spent dialysate from the peritoneal cavity. The number of fill/dwell/drain cycles that are required during a given APD session depends upon the total volume of dialysate prescribed for the patient's APD regime.
APD can be and is practiced in different ways.
Continuous Cycling Peritoneal Dialysis (CCPD) is one commonly used APD modality. During each fill/dwell/drain phase of CCPD, the cycler infuses a prescribed volume of dialysate. After a prescribed dwell period, the cycler completely drains his liquid volume from the patient, leaving the peritoneal cavity empty, or "dry." Typically, CCPD employs 6 fill/dwell/drain cycles to achieve a prescribed therapy volume. After the last prescribed fill/dwell/drain cycle in CCPD, the cycler infuses a final fill volume. The final fill volume dwells in the patient through the day. It is drained at the outset of the next CCPD session in the evening. The final fill volume can contain a different concentration of dextrose than the fill volume of the successive CCPD fill/dwell/drain fill cycles the cycler provides.
Intermittent Peritoneal Dialysis (IPD) is another APD modality. IPD is typically used in acute situations, when a patient suddenly enters dialysis therapy. IPD can also be used when a patient requires PD, but cannot undertake the responsibilities of CAPD or otherwise do it at home. Like CCPD, IPD involves a series of fill/dwell/drain cycles. The cycles in IPD are typically closer in time than in CCPD. In addition, unlike CCPD, IPD does not include a final fill phase. In IPD, the patient's peritoneal cavity is left free of dialysate (or "dry") in between APD therapy sessions.
Tidal peritoneal Dialysis (TPD) is another APD modality. Like CCPD, TPD includes a series of fill/dwell/drain cycles. Unlike CCPD, TPD does not completely drain dialysate from the peritoneal cavity during each drain phase. Instead, TPD establishes a base volume during the first fill phase and drains only a portion of this volume during the first drain phase. Subsequent fill/dwell/drain cycles infuse then drain a replacement volume on top of the base volume, except for the last drain phase. The last drain phase removes all dialysate from the peritoneal cavity. There is a variation of TPD that includes cycles during which the patient is completely drained and infused with a new full base volume of dialysis. TPD can include a final fill cycle, like CCPD. Alternatively, TPD can avoid the final cycle, like IPD.
APD offers flexibility and quality of life enhancements to a person requiring dialysis. APD can free the patient from the fatigue and inconvenience that the day to day practice of CAPD represents to some individuals. APD can give back to the patient his or her waking and working hours free of the need to conduct dialysis exchanges.
For these reasons, it would be desirable to provide improved methods, apparatus, and kits for performing peritoneal dialysis. In particular, it would be desirable to perform flow-through dialysis without the need to employ a pair of transcutaneously implanted catheters or in some cases even a single transcutaneously implanted catheter. Alternatively, it would be desirable to perform flow-through tidal peritoneal dialysis in combination with certain advantageous aspects of flow-through dialysis, while preferably retaining the benefits of requiring only a single access site, and more preferably relying on a single percutaneous access location. Such methods, apparatus, and kits should be readily adaptable for home use and minimize the risk of infection in both the home and out-of-the-home environments. At least some of these advantages will be met by the invention described hereinafter.
2. Description of the Background Art
Conventional peritoneal dialysis tubing sets and components are described in U.S. Pat. Nos. 4,306,976; 4,396,382; 5,250,041; 5,334,139; 5,338,293; and 5,423,768. U.S. Pat. No. 4,184,497 describes an implantable catheter having an enlarged hollow portion which can be punctured to receive a sterile access needle. U.S. Pat. No. 4,496,349 describes a septum-type transcutaneous access port. Co-pending application Ser. No. 08/896,791, filed on Jul. 18, 1997, and assigned to the assignee of the present application, describes a dialysis tubing set which could be used in the methods and systems of the present invention. The full disclosures of this application and all listed U.S. patents are incorporated herein by reference.